So the idle on my car is at 15:1 AFR, and the screws are 2 1/2 - 2 /34 of the way out. I have the metering block over at a long time Holley guys shop, and he was going to enlarge the passages by .003, but they are not where they usually are on these metering blocks. To get to the passages, is it through the brass plugs on the bottom of the block? And if so, it looks like those are not going to come out easily. Where do I get replacements?

And is this what I need to do to be able to richen it up at idle, and have the screws in a reasonable place?

Edited by mickm (02/06/1806:00 PM)

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"the orange fun car" 540 Hemi 4 spd 3:54 dana1 of 1 - only FK5 70 Road Runner that used to be a 383 auto now a 540 Hemi Six-Pak 4 spd in existence

Mick, have you tried adjusting the mixture screws in the baseplates of the end carbs? Backing them out maybe 1/8 turn each will make a big difference and take some of the load off your center carb. I have set up more than a few 6 paks and even with big cams, I've never had to open idle passages in the center carb. Good luck!

Mick, have you tried adjusting the mixture screws in the baseplates of the end carbs? Backing them out maybe 1/8 turn each will make a big difference and take some of the load off your center carb. I have set up more than a few 6 paks and even with big cams, I've never had to open idle passages in the center carb. Good luck!

VERY good advice.

Also, I am not aware of any metering block idle mixture passages under the metering block behind plugs???

There are main circuit passages behind the power valve at 3 o'clock & 9 o'clock that can be enlarged per the old Direct Connection book, but I don't recommend doing it. There are also some holes up in the top corners (name?) that can be enlarged too, but again I don't recommend it.

I know you have that big stroker hemi six pack, so maybe consider Promax parts instead of modifying stock pieces. You can get adjustable metering bodies & adjustable metering plates.... but try the outboard idles screws first like Lee says. THOSE are behind lead plugs on the front of the baseplates for the outer carburetors. Hope this helps.

Mick, have you tried adjusting the mixture screws in the baseplates of the end carbs? Backing them out maybe 1/8 turn each will make a big difference and take some of the load off your center carb. I have set up more than a few 6 paks and even with big cams, I've never had to open idle passages in the center carb. Good luck!

Best idle on a small block Sixpak setup with an XE268 cam ended up with the mixture screws on all 3 carbs out 1 5/8 turns. Covering the corresponding air bleed one at a time will tell you which direction to go with the mixture screw. Never had to drill anything.

Mick, have you tried adjusting the mixture screws in the baseplates of the end carbs? Backing them out maybe 1/8 turn each will make a big difference and take some of the load off your center carb. I have set up more than a few 6 paks and even with big cams, I've never had to open idle passages in the center carb. Good luck!

Best idle on a small block Sixpak setup with an XE268 cam ended up with the mixture screws on all 3 carbs out 1 5/8 turns. Covering the corresponding air bleed one at a time will tell you which direction to go with the mixture screw. Never had to drill anything.

I have done that following the writeup from Dayclona, and have the end carbs, as far as I can tell, adjusted properly, in that when I cover the air bleeds one at at time, there is no change in the idle. There was when I first put the carbs on, so I know there was a change.

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"the orange fun car" 540 Hemi 4 spd 3:54 dana1 of 1 - only FK5 70 Road Runner that used to be a 383 auto now a 540 Hemi Six-Pak 4 spd in existence

So the idle on my car is at 15:1 AFR, and the screws are 2 1/2 - 2 /34 of the way out.

What is wrong with that I like to see above 14.5 AFR at idle when warm or hot to help keep the plugs clean My old pump gas Duster 6 pack set up ran at or above 15.2 AFR at idle and low part throttle high manifold vacumme cruise up to 2300 RPM That rascal flat rocked

So the idle on my car is at 15:1 AFR, and the screws are 2 1/2 - 2 /34 of the way out.

What is wrong with that I like to see above 14.5 AFR at idle when warm or hot to help keep the plugs clean My old pump gas Duster 6 pack set up ran at or above 15.2 AFR at idle and low part throttle high manifold vacumme cruise up to 2300 RPM That rascal flat rocked

Damn good question! It started with me asking a couple of very experienced engine builders why my car stinks so bad at idle. I thought running rich would make it stink, an they both said, "because it's running too lean."

So, in an attempt to richen it up to see where that would get me, and knowing that for a Holley, almost 3 turns out on the idle screws is not optimal, I was attempting to get the idle screws to a more normal position, to give a range of control over the mixture.

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"the orange fun car" 540 Hemi 4 spd 3:54 dana1 of 1 - only FK5 70 Road Runner that used to be a 383 auto now a 540 Hemi Six-Pak 4 spd in existence

To see if enrichening helps the idle air fuel ratio helps you gain better control of the idle mixture try using some very thin wires formed like a J stuck upside down into all six idle air bleeds Let us know your results

Damn good question! It started with me asking a couple of very experienced engine builders why my car stinks so bad at idle. I thought running rich would make it stink, an they both said, "because it's running too lean."[/quote]

My EFI car smelled bad at idle as well. It has a pretty healthy roller cam in it. That was with an oxygen sensor feeding back to the ECM.

I welded a pair of metal matrix, racing catalytic converters on it and the problem was solved. It didn't affect the power output either.

I've drilled and tap (6x32)several Dominator body to add idle and transition fuel restrictors to help lean them down to make them have 14.25 or leaner at idle or on the low part throttle opening on the transition circuits I've never had a motor smell rich from being to lean at idle Maybe I should get my old LM1 system hook up on my 1966 Dodge street car and experiment some with it to learn some more

To see if enrichening helps the idle air fuel ratio helps you gain better control of the idle mixture try using some very thin wires formed like a J stuck upside down into all six idle air bleeds Let us know your results

Good deal on holley sending you the new metering plate, its always been hit and miss on the idle restrictors. Whoever is helping you is right, center needs more fuel to get to 1 turn out on the idle screws with proper air fuel reading. You may also need smaller main jets after doing that. If you look up the venturi size of the center and use a double pumper front plate that matches that venturi,600 or 650 I think, that works too and most old double pumpers have idle jets down low where you can drill them.